GESTRA SRL 6-50 User manual

1
EN
English
Original Installation Instructions
819117-04
Logic unit
SRL 6-50

2
Contents
Important Notes
Usage for the intended purpose ..............................................................................................................3
Function ............................................................................................................................................3– 4
Safety note .............................................................................................................................................4
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility) .......................................................5
ATEX (Atmosphère Explosible).................................................................................................................5
Note on the Declaration of Conformity / Declaration by the Manufacturer ..........................................5
Page
Replacing and disposing of the logic unit
Replacing the logic unit.........................................................................................................................20
Disposal................................................................................................................................................20
In the system: Installing the logic unit
Dimensions SRL 6-50.............................................................................................................................8
Key.........................................................................................................................................................8
Installing logic unit SRL 6-50 .................................................................................................................8
Name plate / marking .............................................................................................................................9
SRL 6-50..........................................................................................................................................6 – 7
Scope of supply ......................................................................................................................................7
Technical data
Basic Settings
Factory setting......................................................................................................................................14
In the system: Wiring the logic unit
Wiring diagram for logic unit SRL 6-50 ................................................................................................10
Key.......................................................................................................................................................11
Tools.....................................................................................................................................................12
Wiring terminal strip ............................................................................................................................13
Start, Operation, Alarm and Test
SRL 6-50......................................................................................................................................14 – 18
Troubleshooting
Indication, diagnosis & remedy ....................................................................................................... 19-20

3
Important Notes
Usage for the intended purpose
The logic unit SRL 6-50 is used in conjunction with the level switches NRS 1-50, NRS 1-51 for moni-
toring the separate rinsing of the connecting lines leading to the level pots of externally installed water
level limiters or high level alarms.
If the level electrode (high / low level limiter) is installed in an isolatable level pot outside the boiler,
make sure that the level pot is drained and the connecting lines are rinsed at regular intervals.
For this purpose the connecting lines must be shut off and opened at regular intervals and by opening
and closing the drain valve the lines and the level pot will be rinsed.
During the rinsing process the water level cannot be measured in the level pot for 5 minutes. The level
switch NRS 1-50, NRS 1-51 therefore bypasses the level electrode and monitors the rinsing and bypass
time (standby input, controlled by the logic unit SRL 6-50).
Fig. 1 shows a water-level limiter system with a level electrode installed inside the boiler and a second
electrode installed in an external level pot. The following combination is also possible: 2 external level
electrodes NRG 1X-5X, 2 logic units SRL 6-50, 1 level switch NRS 1-50, NRS 1-51.
The logic unit monitors the following times and process sequences:
Interval time: This is the time interval at which, depending on the operating mode (24h / 72h boiler
operation without constant supervision), the connecting lines have to be rinsed. The interval time starts
when the logic unit is switched on.
Fig. 1
Function
Niveauschalter
NRS 1-50
Überwachungslogik
SRL 6-50
D
E
F
Niveauelektrode
NRG 1x-11, NRG 1x-50
NRG 16-36
Level electrode
NRG 1x-11, NRG 1x-50
NRG 16-36
Level switch
NRS 1-50
Logic unit SRL 6-50

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Important Notes - continued -
Function - continued -
During operation the standby time is started after the interval time has elapsed and the interval time is
reset to its initial value.
During the standby time the connecting lines must be rinsed.
Synchronizing: When valve D or E closes, the purging time starts and the interval time is reset to its
initial value. The purging time can start any time. The purging time also starts when the logic unit is
switched on and after the standby time has elapsed.
Once the purging time has started the stand-by input of the level switch NRS 1-50, NRS 1-51 will also
be activated.
During the purging time all valves must be opened and closed in a fixed sequence. The logic unit polls
the limit switches to obtain data on the valve positions and the level switch for information on the water
level (low level if electrode is exposed).
If valves D and E are open after the rinsing process and valve F closed and the level electrode for low
water (low level) is submerged again, the stand-by input of the level switch NRS 1-50, NRS 1-51 will be
deactivated.
The stand-by time of the level switch is limited to a maximum of 5 minutes. If the stand-by input is not
deactivated by the logic unit during this time, the level switch will open the safety circuit.
Safety note
The equipment fulfils a safety function and must only be installed and commissioned by qualified and
competent staff.
Retrofitting and maintenance work must only be performed by qualified staff who – through adequate
training – have achieved a recognised level of competence.

5
ATEX (Atmosphère Explosible)
According to the European Directive 2014/34/EC the equipment must not be used in explosion risk
areas.
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility)
The equipment meets the requirements of the Low Voltage Directive 2014/35/EC and the
EMC Directive 2014/30/EC.
Note on the Declaration of Conformity / Declaration by the Manufacturer
For details on the conformity of our equipment according to the European Directives see our Declara-
tion of Conformity or our Declaration of Manufacturer.
The current Declaration of Conformity / Declaration of Manufacturer are available in the Internet under
www.gestra.com/documents or can be requested from us.
Important Notes - continued -

6
Technical data
SRL 6-50
Supply:
Supply voltage
24 VDC +/– 20 %, 0.1 A
Fuse
External 0.5 A (semi-delay), without external wiring (indicators)
Power consumption
4 VA
Inputs:
Wiring of limit switches, level switches NRS 1-50, NRS 1-51
5 volt-free contacts of the limit switches of the valves
1 volt-free contact of the level switch NRS 1-50, NRS 1-51
1 signal input for switching between water level limiter / high level alarm
1 signal input for switching between steam boiler / hot-water installation
Outputs:
4 change-over contacts, 8 A, 30 V DC, cos ϕ= 1 (IEC 61810)
for messages:
Standby on/off (at level switches NRS 1-50, NRS 1-51)
Standby time (Start) running,
Purging time (Standby) running
Deactivated (Stop)
Times:
Interval time
1 - 9999 hours, adjustable
Standby time
1 - 99 hours, adjustable
Purging time
5:10 minutes, factory set
Other time settings on request
Equipment design:
Indicators and adjustors
1 indicating & operating display,
1 green LED indicating standby time (Start),
1 amber LED indicating purging time (Standby)
1 red LED indicating deactivation (Stop)
Housing
Case for wall mounting with see-through lid, hinge and latch.
Casing material: ABS, polycarbonate
Cable entry / electrical connection
1 14pole spring-loaded terminal strip, conductor size 2.5 mm2
Cable gland with integrated cable clamp 1 x M20 x 1.5
1 Female connector M12 of sensor, with 8 poles

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Technical Data - continued -
SRL 6-50
Protection class
2 (completely insulated)
Protection
IP 65 to EN 60529
Weight
approx. 1.3 kg
Further conditions:
Ambient temperature
when system is switched on: 0 °C ... 55 °C,
during operation: –10 °C ... 55 °C
Transport temperature
–20 °C ... +80 °C (< 100 hours),
defrosting time of the de-energized equipment before it can be put into operation: 24 hours.
Storage temperature
–20 °C ... +70 °C,
defrosting time of the de-energized equipment before it can be put into operation: 24 hours.
Relative humidity
max. 95 %, no moisture condensation
Scope of supply
SRL 6-50
1 Logic unit with enclosure for wall mounting
1 Connecting cable, length 5 m, one end fitted with female M12 connector, with 8 poles
1 Installation & operating manual

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Wandlaschen
Start
Service
Stop
Standby
ES OCK
In the system: Installing the logic unit
Dimensions of SRL 6-50
Fig. 2
Installing logic unit SRL 6-50
The enclosure of the logic unit is designed for wall mounting and should be installed close to the
external level pot.
1 Latch
2Lugs for wall mounting
3Indicator and adjustor pad
4Start LED, green (stand-by time)
Key
5Standby LED, yellow (purging time)
6Stop LED, red (deactivation)
7Lid for terminal block
8Cover screws
2
1
3
4
5
6
7
8 8
2
143
130
116
113
5.2
185
164
176.5
54.5
116
69
Lugs for wall
mounting

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SRL 6-50
IP 65
24 VDC
Tamb =55°C(131°F)
Intervallzeit: xx
Bereitschaftszeit: x
Spülzeit:
h
h
xmin.
4W
Software-Nr.: xxxxxx-xx
Mat.Nr.: xxxxxx
Fig. 3
In the system: Installing the logic unit - continued -
Name plate / marking
Safety note
Type designation
Supply voltage
Power consumption
Ambient temperature
Protection
Times
Disposal note
Manufacturer
Attention
The name plate specifies the technical features of the equipment. Note that any piece of
equipment without its specific name plate must neither be commissioned nor operated.
Standby time:
Purging time:
Wiring diagram no.: 821603.xx
Software no.:
Material no.: 392708

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In the system: Wiring the logic unit
Wiring diagram for logic unit SRL 6-50
+
+
12345678 1
1
2
2
20
29
7
15
21
30
6
14
3
3
4
4
5678 9 10 11 12 13 14
1
1
1
6
3
35
5
7
9
10
2
24
4
6
8
2345678
Fig. 4
9d
e
f
i
j
k
bg
a
Valve D OPEN
Valve D CLOSED
Valve E OPEN
Valve E CLOSED
Valve F CLOSED
c
m
g
l
n
h
h
0
Number
of single
core
Color of
single core
1 white (WH)
2 brown (BN)
3 green (GN)
4 yellow (YE)
5 grey (GY)
6 pink (PK)
7 blue (BU)
a

11
In the system: Wiring the logic unit - continued -
9Female connector of sensor M12, with 8 poles
0Male connector of sensor M12, with connecting cable
aConductor marking at one end of the connecting line
bTerminal box (provided on site), installed close to level pot
cLimit switch of valve
dSpring-loaded terminal strip with 14 poles, conductor size 2.5 mm2
eExternal bridge on terminals 6 / 7 for high level alarm (level electrode NRG 1X-51)
fExternal bridge on terminals 5 / 8 for water level limiter (level electrode NRG 1X-50)
in hot-water plants
gTerminals in control cabinets for providing the supply voltage and for
connecting the logic unit and the level switch
hConnection for supply voltage 24 V DC with 0.5 A semi-delay fuse provided on site
(see “Technical Data”)
iExternal indication of deactivation (Stop), 24 DC 1A
jExternal indication of purging time (Standby), 24 DC 1A
kExternal indication of standby time (Start), 24 DC 1A
lLevel switch NRS 1-50, NRS 1-51, connection: first standby input and first signal output
mSecond logic unit SRL 6-50
nLevel switch NRS 1-50, connection: second standby input and second signal output
Key

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In the system: Wiring the logic unit - continued -
We recommend to use the same safety power supply unit in order to supply the logic
unit SRL 6-50 and the level switches NRS 1-50, NRS 1-51 with 24 V DC.
Note
Tools
Screwdriver, size 2.5, completely insulated according to VDE 0680-1
Screwdriver, size 2
Danger
For the supply of the logic unit SRL 6-50 with 24 V DC use a safety extra-low voltage
(SELV) power supply unit that must be electrically isolated from dangerous contact
voltages and must meet at least the requirements on double or reinforced isolation
acc. to DIN EN 50178 or DIN EN 61010-1 or DIN EN 60730-1 or DIN EN 60950 (safe
electrical isolation).
Any item of equipment that you want to connect to terminals 6, 7, 14, 15 (standby
input 1 / 2) of level switch NRS 1-50, NRS 1-51 must be certified to have at least
double or reinforced isolation according to DIN EN 50178 or DIN EN 61010-1 or DIN
EN 60730-1 or DIN EN 60950 (safe isolation) between the standby inputs, the signal
outputs and the live parts of the installation that are not supplied with safety extra-low
voltage.
Attention
Fuse the logic unit with an external 0.5 A semi-delay fuse (see “Technical Data”).
To connect the level electrode NRG 1X-51 / level switch NRS 1-51 (high level alarm)
bridge terminals 6 and 7 with a wire link.
To connect the level electrode NRG 1X-50 / level switch NRS 1-50 (water level limiter,
application in hot-water installation) bridge terminals 5 and 8 with a wire link.
If external indicator lights are connected the logic unit must supply them with 24 V DC.
Install connecting lines to the logic unit and to the limit switches separated from power
cables.
Do not use unused terminals as support point terminals.

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Wiring terminal strip
Wire the terminal strips according to the wiring diagram Fig. 4.
To connect the limit switches please provide a terminal box (protection IP 65) close to the level pot
Fig. 4.
The level pot is provided with three shut-off valves. Both valves D and E are fitted with two limit
switches for “OPEN” position (D 1 / E 1) and “CLOSED” position (D 2 / E 2).
The drain valve F is fitted with only one limit switch for the "CLOSED" position.
To connect the terminal box and the logic unit please use the supplied connecting cable and wire the
terminals in accordance with the wiring diagram Fig. 4.
It is possible to connect external indicator lights to terminals 10 to 12. For this purpose screw an ad-
ditional cable gland M20 x 1.5 into the housing. The bore for the second cable gland is pre-punched
and must be knocked out.
Insert the male connector of the connecting cable into the female connector of the logic unit and fix it
in place by turning the knurled nut.
In the system: Wiring the logic unit - continued -
Basic Settings
Factory settings
Logic unit SRL 6-50
The logic unit features the following factory set default values:
Interval time: 24 hours
Standby time: 1 hour
Purging time (SRL 6-50): 5:10 minutes

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Start, Operation, Alarm and Test
SRL 6-50
Fig. 6
SRL6-50
ESC OK
Start LED, green
(standby time)
Standby LED, amber
(purging time)
Stop LED, red
(deactivation)
Display &
adjustor pad
Service
Start
Standby
Stop
Purging
Val D OPEN:
Val E CLOSED:
Val F CLOSED:
Start
Activity Indicator & adjustor pad LED indication Function
Switch on supply voltage.
All LEDs are illumi-
nated for 3 sec., then
only the Start LED
remains illuminated.
Initialising,
takes approx. 40 sec.
After applying the supply voltage
initiate the first purging process.
To continue see indication of
sequence schedule for purging.
Standby LED illumi-
nated
Purging time running,
standby input activated
(NRS 1-5X)
Please wait
until limiter
is ready
Operation
Activity Indicator & adjustor pad LED indication Function
Interval time elapsed and re-
started Start LED illuminated Standby time running
Initiate purging process,
see sequence schedule for
purging.
Start LED
not illuminated
Standby LED illumi-
nated
Purging time running,
standby input activated
(NRS 1-5X)
Purging
Valve D OPEN (CLOSED)
Valve E CLOSED
Valve F CLOSED
Purging
Valve D OPEN (CLOSED)
Valve E CLOSED
Valve F CLOSED

15
Sequence schedule for purging
Steam boiler Hot-water plant
02:46m
Valve D OPEN
Valve E OPEN
Valve F CLOSED
Start, Operation and Alarm - continued -
SRL 6-50 - continued -
When operating the valves Fig. 7 follow the sequence schedule indicated in the display
& adjustor pad. The individual steps are listed in chronological order.
Note
Valve D
Valve E
Valve F
Boiler
LW
Fig. 7
Purging
Valve D OPEN
Valve E CLOSED
Valve F CLOSED
Purging
Valve D CLOSED
Valve E CLOSED
Valve F CLOSED
04:13m
Valve D OPEN
Valve E CLOSED
Valve F OPEN
03:56m
Awaiting
low level message
37 sec.
03:21m
Valve D CLOSED
Valve E CLOSED
Valve F OPEN
03:02m
Valve D CLOSED
Valve E OPEN
Valve F OPEN
Remaining purging time
Awaiting low level message (only with level
electrode NRG 1X-50, low-level limiter)
02:36m
Awaiting
normal
level
04:13m
Valve D CLOSED
Valve E CLOSED
Valve F OPEN
03:56m
Awaiting
low level message
37 sec.
03:21m
Valve D CLOSED
Valve E CLOSED
Valve F CLOSED
03:02m
Valve D OPEN
Valve E CLOSED
Valve F CLOSED
02:46m
Valve D OPEN
Valve E OPEN
Valve F CLOSED
02:36m
Awaiting
normal
level
Purging finished
Action Indicator & adjustor pad LED indication Function
Purging finished.
Indication of interval time &
remaining time
All LEDs are not
illuminated.
Standby input
deactivated (NRS 1-5X)
Interval:
24h
Remaining:
23h 59m
First close valve F.
Then slowly open valve D.

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Changing standby and interval time
Action
Indicator & ajdustor pad Function
Press button and simultaneously.
The password input box
opens.
To enter the password press and hold down
until the input line is activated and highlighted.
Briefly press . The input mask appears.
The input mask appears
and you can enter the
password 003503.
Use buttons to enter the password 003503.
To jump back and forth between the digits use
buttons .
To confirm the password press button
and then . The next mask appears. The password is confirmed.
If the entered password is incorrect the system displays a flashing message: Password incorrect. You have
to enter the password within 60 seconds otherwise your entry will not be applied and you have to repeat the
procedure.
Start, Operation and Alarm - continued -
SRL 6-50 - continued -
Fig. 6
SRL6-50
ESC OK
PW input
0
Press ESC > 1
sec. and OK to
confirm
ESC
ESC
OK
OK
ESC
PW input
000000
Press ESC > 1
sec. and OK to
confirm
0
Start LED, green
(standby time)
Standby LED, amber
(purging time)
Stop LED, red
(deactivation)
Display &
adjustor pad
Service
Start
Standby
Stop
Purging
Val D OPEN:
Val E CLOSED:
Val F CLOSED:

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Start, Operation and Alarm - continued -
SRL 6-50 - continued -
Changing the standby time
Action
Indicator & ajdustor pad Function
To enter the standby time press and hold button
until the input line is highlighted.
The input mask appears
and you can enter the new
standby time.
Briefly press button . The input mask appears.
Use buttons to enter the digits. To jump back
and forth between the digits use buttons .
Press button . The entry is confimed.
Standby time
01:00 h
To change the
setting press
ESC > 1 sec. and
confirm with OK
ESC
OK
OK
ESC
Changing the interval time
Action
Indicator & ajdustor pad Function
To change the interval time press buttons and
simultaneously.
The input mask appears
and you can enter the new
interval time.
The entry is confimed.
To enter the interval time press and hold button
until the input line is highlighted.
Briefly press button . The input mask appears.
Use buttons to enter the digits. To jump back
and forth between the digits use buttons .
Press button .
Interval time
01:00 h
To change the
setting press
ESC > 1 sec. and
confirm with OK
ESC
OK
OK
Attention
To determine the interval and standby time please consult the expert for the plant
system.

18
Start, Operation and Alarm - continued -
SRL 6-50 - continued -
Attention
It is not permitted to purge two measuring pots (including the connecting lines) at the
same time.
If standby inputs 1 and 2 of the level switch are activated at the same time, the level
switch will open the safety circuit.
Danger
Please check positions of valves after each purging process. The valves must be in
operating position, which means that valves D and E must be open and valve F closed.

19
Possible operating errors
Error Position of
valves
Indicator & adjustor
pad LED indication* Remedy
Purging time
elapsed without
purging
Operating
position
Valve D OPEN
Valve E OPEN
Valve F
CLOSED
Standby LED not
illuminated,
Stop LED illuminated
for approx. 40 sec.,
then Start LED lights up
(standby time)
Initiate purging during
standby time
Purging not fin-
ished successfully
during the preset
purging time
(5 min)
Operating
position
Standby LED not
illuminated,
Stop LED illuminated
for approx. 40 sec.,
then Start LED lights up
(standby time)
Initiate purging during
standby time
Purging not fin-
ished successfully
during the preset
purging time
(5 min)
Not in operat-
ing position
Standby LED not
illuminated,
Stop LED illuminated
for approx. 40 sec.,
then Standby LED lights
up again
(purging time)
Initiate purging during
purging time
For installations with two measuring pots
Purging time for
measuring pot 1
running, purging
for measuring
pot is started in
parallel
Operating
position
Indicated sequence as
specified above
Standby LED not
illuminated,
Stop LED illuminated
for approx. 40 sec.,
then Start LED lights up
(standby time)
Move all valves to
operating position.
Both logic units re-start
with standby time.
Now purge both meas-
uring pots one after the
other.
Purging time for
measuring pot 1
running, purging
for measuring
pot is started in
parallel
Not in operat-
ing position
Standby LED not
illuminated,
Stop LED illuminated
for approx. 40 sec.,
then Standby LED lights
up again
(purging time)
*after SRL internal purging time (5 minutes 10 seconds) has elapsed
Purging must be
repeated.
End of purging time
Waiting for NRS 1-50/51
appears alternately for
approx. 40 sec.
then the following
appears:
Purging
Valve D OPEN (CLOSED)
Valve E CLOSED
Valve F CLOSED
Troubleshooting
Indication, diagnosis & remedy

20
Replacing and disposing of the logic unit
For the disposal of the equipment observe the pertinent legal regulations concerning waste disposal.
Replacing the logic unit
1. Switch off supply voltage.
2. Undo cover screws 8and remove cover for terminal block 7. (Fig. 2)
3. Unplug control cables from terminal strip dand pull cables out of the cable gland.
4. Detach connecting cables for limit switches.
5. Remove the logic unit.
6. Install and connect new logic unit.
7. Attach connecting cables for limit switches.
8. Switch on supply voltage
9. Initiate first purging process.
Disposal
If faults occur that are not listed above or cannot be corrected, please contact our service centre or
authorized agency in your country.
Indication, diagnosis & remedy - continued -
Troubleshooting - continued -
Fault in program sequence, safety circuit in level switch interrupted
Error Remedy
Display & adjustor pad signals “Limit switch defective”. Replace defective limit switch.
Failure of voltage supply during purging time, standby
input deactivated and safety circuit interrupted
(NRS 1-5X).
Apply supply voltage, continue purging process.